This invention relates to a device for supporting and sealing a final drive shaft bearing for use in a speed change gear having the construction in which the final drive shaft is supported by a bearing holder via a rolling element bearing and the bearing holder is fitted and fixed to a gear cox.
The present invention is directed to provide a device of the above-mentioned type having a simplified construction with a small number of components in which the rolling element bearing is firmly fitted to the bearing holder and the leak of a lubricant passing through the rolling element bearing can be reliably prevented inside the bearing holder.
In accordance with the present invention, in order to accomplish the above object, there is provided a device for supporting and sealing a final drive shaft bearing in a speed change gear which comprises a gear box; a bearing holder fitted and fixed to the gear box and having a stopper flange at the inner end thereof; a final drive shaft supported by the bearing holder via a rolling element bearing, the rolling element bearing having an outer race and an inner race; a first nut screwed to the outer end portion of the bearing holder and clamping the outer race of the rolling element bearing in cooperation with the stopper flange at the inner end portion of the bearing holder; a seal housing formed integrally with the bearing holder and extending outside the first nut screwed to the bearing holder; and an oil seal disposed in the seal housing and having a seal lip coming into contact with the outer circumferential surface of the drive shaft.
The construction described above makes it possible to firmly fit the rolling element bearing to the bearing holder and to support always and stably the final drive shaft.
The seal housing is integrally formed with the bearing holder so as to extend outside the nut and the oil seal coming into contact with the outer circumferential surface of the final drive shaft is fitted to the seal housing. This arrangement eliminates the necessity of disposing an exclusive member for the seal housing and the device having a simple construction can be produced at a reduced cost of production. Moreover, since a part of the inner circumferential surface of the bearing holder serves also as the inner circumferential surface of the seal housing, the rolling element bearing and the oil seal can be easily aligned coaxially, thereby preventing deflection of the axis of the seal lip of the oil seal. Hence, the oil seal can exhibit its full function and can reliably prevent the leak of a lubricant passing through the rolling element bearing. The oil seal also protects the screw portion of the nut from external dust and mud water and prevents luster so that disassembly and maintenance can be easily made.
According to one embodiment of the present invention, the final drive shaft is equipped with a helical bevel gear and the rolling element bearing consists of one double-row angular contact type bearing. Further, a second nut is screwed to the final drive shaft to clamp the inner race of the bearing in cooperation with the bevel gear. With this arrangement, the bevel gear can be strongly supported on the bearing holder in the radial direction as well as in the axial direction via one double-row angular contact type bearing and the two nuts. Therefore, even if the direction of a thrust load acting upon the helical bevel gear changes together with conversion of the power transmitting direction, the thrust load can be always transmitted to and borne by the bearing holder via the bearing and the displacement of the gear in the axial direction can be reliably restricted. In consequence, back-lash of the engaging portion of the gear with a mating bevel gear can be prevented.
The device of the invention reduces the number of necessary components and is simple in construction. In addition, an assembly of the bearing holder and the helical bevel gear is produced in advance and is fitted to the gear box so that the device as a whole can be easily assembled with an extremely high level of productivity.